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1.
What to say to someone when they're getting too excited about something (can be anything).

Another way of saying "Calm down!".
A: (Person getting too excited about something)

B: Ok man, keep your pants on!
by El_Barto October 20, 2004
 
2.
Stop flipin out.
After being punked, I told him to keep his pants on
by Stephen Carboni April 20, 2004